Statistical Methods
The statistical analyses were performed with IBM SPSS Statistics V.22.0 (SPSS Inc, Chicago). Continuous variables were summarized as means±SDs for normal distribution data and as median (interquartile range) for abnormal distribution data. Independent-samples t test (for normal distribution data), Mann-Whitney U tests (for abnormal distribution data), or Chi-square (for categorical variables) was used to compare parameters in the two groups. Proportions were compared using the χ2 test or by linear-by linear χ2 association test in case of ordinal categorical variables. Univariate and multivariate analyses were performed to analyze the influence of each factor on PICU mortality. The ability of factors to predict hospital mortality was tested using receiver operating characteristic (ROC) curve performed using STATA 15.0 MP (College Station, Texas, USA). Cut-off values were identified using the highest Youden index (sensitivity + specificity-1)[11]. Significance was taken as a P value less than 0.05.